Mexico City, June 27 (bdnews24.com/Reuters) - A Mexican police chief and his bodyguard were shot to death as they ate lunch in Mexico City on Thursday, the latest police slaying in a drug war that has killed more than 1,600 people this year.

A heavily armed gunman burst into a restaurant in the north of the capital and shot Igor Labastida, a regional director for trafficking and contraband in Mexico's federal police force, and three bodyguards, a police spokesman said.

"The aggressor entered through one of the two doors in the restaurant and opened fire on Labastida and his companions," Mexico's federal police said in a statement.

Police said one bodyguard was killed and two others were seriously injured, clarifying an earlier police report that three police were murdered along with Labastida.

And police said a single gunmen perpetrated the attack, not several men, as a spokesman had said earlier.

The murder of Labastida, who survived an attempt on his life in 2003, comes amid a rash of police killings as an army crackdown on drug cartels intensifies battles over turf and protection rings.

Last month one of Mexico's top federal police chiefs, Edgar Millan, was killed by hitmen linked to a powerful drug cartel from the Pacific state of Sinaloa as he returned to his apartment in Mexico City.

Some 500 police officers have been killed in drug violence since Mexican President Felipe Calderon launched his military-backed anti-drug offensive in December 2006.

Calderon's deployment of some 25,000 troops and federal police across Mexico has intensified drug violence, and gangs appear to be targeting more top police officers in Mexico City, who were once thought to be untouchable.